# Math Help - A model rocket...

1. ## A model rocket...

A model rocket is launched straight into the air and its velocity t seconds after engine ignition is decribed by v(t)=50t/a+t^2 feet per second,where 'a' is some positive number.If the rocket begins to decelerate at exactly t=2 seconds,then what is a?

2. Originally Posted by mathcalculushelp
A model rocket is launched straight into the air and its velocity t seconds after engine ignition is decribed by v(t)=50t/a+t^2 feet per second,where 'a' is some positive number.If the rocket begins to decelerate at exactly t=2 seconds,then what is a?
the acceleration, $a(t)$ , changes sign when the rocket begins to decelerate ...

$a(2) = v'(2) = 0$